The purpose of these studies is to apply two dimensional echocardiography to physiological problems in cardiac surgery. The research has both laboratory and clinical phases. Two dimensional ultrasound will be used to calculate dimensional data for the left ventricle including ejection fraction, ventricular volume, and mass/wall thickness. These data will be combined during cardiac surgery with measurements of left ventricular pressure-dP/dt, thermal dilution cardiac output, and aortic flow velocity. A computerized model will calculate changes in left ventricular mechanics resulting from common surgical procedures. These data will be utilized to construct anticipated ventricular performance profiles for common lesions and thereby to stimulate improvement in surgical methods and techniuqes for myocardial preservation. Laboratory and clinical echo data will be calibrated by comparison with preoperative x-ray contrast angiography and radionuclide angiography.